U.S. patent number 5,496,326 [Application Number 08/328,137] was granted by the patent office on 1996-03-05 for fixation screw and method for ligament reconstruction.
Invention is credited to Lanny L. Johnson.
United States Patent |
5,496,326 |
Johnson |
March 5, 1996 |
Fixation screw and method for ligament reconstruction
Abstract
A screw for fixation of a tendon/bone graft during an
arthroscopic surgical procedure includes a smooth conical forward
end having a rounded tip and a spiral thread running from a
position behind the smooth rounded forward end to a rearward end of
the screw. The depth of the thread is shallower than a conventional
screw and the exterior edge of the thread is rounded to decrease
cutting and fragmentation of the tendon and bone. The screw
includes an internal bore with left- and right-handed threaded
portions for engagement with insertion and extraction instruments.
In the method, the bone graft is harvested and sized as desired. A
graft socket is drilled in the bone and then serially sized with
increasingly larger sizing instruments to compact the bone and size
the graft socket to the graft. A smooth bore screw socket is
created by serially dilating a space between the graft and graft
socket with increasingly larger dilating instruments, thereby also
compacting the graft. The appropriately sized fixation screw is
then inserted into the screw socket with the insertion instrument
to fix the graft to the bone.
Inventors: |
Johnson; Lanny L. (Okemos,
MI) |
Family
ID: |
24899746 |
Appl.
No.: |
08/328,137 |
Filed: |
October 24, 1994 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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111970 |
Aug 26, 1993 |
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848546 |
Mar 9, 1992 |
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721893 |
Jun 27, 1991 |
5116337 |
May 26, 1992 |
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Current U.S.
Class: |
606/88; 128/898;
606/304; 606/53; 606/79; 606/916 |
Current CPC
Class: |
A61B
17/8625 (20130101); A61B 17/8635 (20130101); A61B
17/864 (20130101); A61B 17/88 (20130101); A61F
2/0805 (20130101); A61F 2/0811 (20130101); A61B
17/861 (20130101); A61B 17/8875 (20130101); A61F
2002/0858 (20130101); A61F 2002/0882 (20130101); Y10S
606/916 (20130101); Y10S 606/908 (20130101) |
Current International
Class: |
A61B
17/88 (20060101); A61B 17/68 (20060101); A61B
17/86 (20060101); A61F 2/08 (20060101); A61B
017/00 () |
Field of
Search: |
;606/80,167,185,191
;128/898 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
Kenneth L. Lambert, M.D., "Vascularized Patellar Tendon Graft with
Rigid Internal Fixation for Anterior Cruciate Ligament
Insufficiency," Patellar Tendon Graft, Jan., Feb. 1983, No. 172,
pp. 85-88. .
Bernard R. Bach, Jr., M.D., "Potential Pitfalls of Kurosaka Screw
Interference Fixation for ACL Surgery," Sports Medicine Section,
Dept. of Orthopedic Surgery, Rush-Presbyterian-St. Luke's Medical
Center, Chicago, pp. 76-82. .
Bernard R. Bach, Jr., M.D., "Arthroscopy-Assisted Patellar Tendon
Substitution for Angerior Cruciate Ligament Insufficiency," Sports
Medicine Section, Dept. of Orthopedic Surgery,
Rush-Presbyterian-St. Luke's Medical Center Chicago, pp. 3-20.
.
Erik Oberg, Franklin D. Jones and Holbrook L. Horton, "Machinery's
Handbook", Twenty First Edition, 1980 pp. 1136, 1207, 1348 and
1374. .
Excerpts from Physician's Current Procedural Terminology, 1990, p.
125. .
Self-Tapping Set Screws, Setko Brochure, Catalog No. 31. .
James F. Sillman, M.D., "The Crucial Choice", Kurosaka Brochure.
.
"Concept Cannulated Interference Screws", Excerpts from the Concept
Brochure, p. 80. .
"When It Comes to ACL, Why Screw Around with Anyone Else", Acufex
advertisement, 1990..
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Primary Examiner: Hafer; Robert A.
Assistant Examiner: Hanlon; Brian E.
Attorney, Agent or Firm: Cushman Darby & Cushman
Parent Case Text
This is a continuation of application Ser. No. 08/111/970, filed on
Aug. 26, 1993, now abandoned, which is a continuation of Ser. No.
07/848,546, filed on Mar. 9, 1992, now abandoned, which is a
divisional of Ser. No. 07/721,893, filed Jun. 27, 1991, now U.S.
Pat. No. 5,116,337, issued on May 26, 1992.
Claims
What is claimed is:
1. A method for fixation of a tendon/bone graft to a bone,
comprising the steps of:
sizing one end of the tendon/bone graft to the desired size;
drilling a graft socket in the bone;
compacting the bone surrounding the graft socket by sizing the
socket with at least one sizing instrument having a diameter
greater than a diameter of the drilled socket;
inserting the sized end of the tendon/bone graft into the sized
graft socket;
compacting the bone of the tendon/bone graft into the graft socket
with at least one dilating instrument, thereby forming a sized
screw socket;
inserting a fixation screw into the sized screw socket.
2. A method as in claim 1, wherein the drilling is done with an
anti-cavitational drill.
3. A method as in claim 1, wherein the bone compacting step is done
with a series of increasingly larger diameter sizing
instruments.
4. A method as in claim 1, wherein the tendon/bone graft compacting
step is done with a series of increasingly larger diameter dilating
instruments.
5. A method as in claim 1, wherein the tendon/bone graft compacting
step further includes compacting with at least one sizing
instrument having a diameter larger than the last used dilating
instrument.
6. A method as in claim 5, wherein the sizing instrument compacting
step is done with a series of increasingly larger diameter sizing
instruments.
7. A method as in claim 1, wherein the screw is inserted with an
insertion device that threads into a first threaded portion of an
internal bore in the screw in a direction of rotation of an
external thread of the screw.
8. A method as in claim 1, wherein the inserted screw may be
extracted with an extraction device that threads into a threaded
portion of an internal bore in the screw in a reverse direction of
rotation of an external thread of the screw.
9. A method as in claim 1, and further comprising the step of
inserting a fixation wire into a radial bore in a rearward portion
of the inserted screw to fix the screw while at least one of an
insertion device and an extraction device is being removed from the
screw.
10. A method of preparing bone for receiving a medical implant,
comprising the steps of:
creating an initial bore having a side wall in the bone;
compacting the bone along the side wall without intentionally
removing bone by inserting within the bore a first sizing
instrument having a diameter greater than the diameter of the
initial bore; and
further compacting the previously compacted bone along the side
wall without intentionally removing bone by increasingly enlarging
the bore by sequentially inserting within the bore at least two
additional sizing instruments having different diameters, each
greater than the diameter of the first sizing instrument, and
having portions inserted within the bore which have a common
geometry.
11. A method as in claim 10, wherein the initial bore is created by
drilling.
12. A method as in claim 11, wherein the drilling is done with an
anti-cavitational drill.
13. A method as in claim 10, wherein the initial bore is created by
inserting a rotatable instrument into the bone.
14. A method as in claim 13, wherein the rotatable instrument
creates the bore by displacing and compacting bone without removing
bone.
15. A method of preparing bone for receiving a medical implant,
comprising the steps of:
creating an initial cavity having a side wall in the bone;
compacting the bone on the side wall of the cavity without
intentionally removing bone by inserting within the cavity a first
sizing instrument having a cross-sectional area greater than a
cross-sectional area of the initial cavity; and
further compacting the previously compacted bone on the side wall
without intentionally removing bone by increasingly enlarging the
cavity by sequentially inserting within the cavity at least two
additional sizing instruments having different cross-sectional
areas, each greater than the cross-sectional area of the first
sizing instrument, and having portions inserted within the cavity
which have a common geometry.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a screw for fixation of a
bone/tendon graft during a surgical procedure and particularly, to
arthroscopic anterior cruciate ligament reconstruction.
2. Related Art
Ligament reconstruction by replacing the ligament with a
tendon/bone graft is well known in the art. For instance, during
arthroscopic knee surgery, a surgeon can form a tunnel through the
tibia, intra articular joint and femur to receive a
bone-tendon-bone graft harvested from the patellar tendon. A
variety of techniques have been employed to secure the
bone-tendon-bone graft, such as tying sutures over ligament
buttons, staples, unicortical screw posts, or interference screws.
An example of one such ligament anchor system is disclosed in U.S.
Pat. No. 4,870,957, which is incorporated by reference herein.
One common example of interference screw is the self-tapping
Kurosaka screw which cuts its own threads into the bone and graft.
With this type of screw, the graft bone plug is sized to be smaller
than the receptive bone tunnel to provide clearance for the screw
to begin self-tapping and threading. However, there are many
disadvantages to such types of screws. Since there is no preformed
channel for the screw to enter, but rather, the screw cuts its own
channel within the clearance between the bone and the graft, the
screw can diverge, reducing screw thread to bone plug contact. The
self-tapping operation cuts into the graft, thereby possibly
causing graft damage or fragmentation. The insertion of the screw
can also cause migration or translocation of the graft.
Further, the Kurosaka type screw is not well secured to the
insertion device and can fall off the insertion device as well as
require a K-wire insertion. The bone tunnel is usually created with
an acorn type drill head which can cause cavitation of the tunnel
wall and the depth of the tunnel is not controlled.
SUMMARY OF THE INVENTION
The preferred exemplary embodiment of the present invention
includes a screw for fixation of a tendon/bone graft to a bone. The
non-selftapping, non-thread cutting screw includes a smooth conical
forward end having a rounded tip. A right-handed spiral thread runs
from a position behind the smooth rounded forward end to a rearward
end of the screw. The depth of the thread is shallower than
conventional interference screws and the thread has a rounded
exterior edge to decrease cutting and fragmentation of the tendon
and bone.
The screw includes an internal longitudinal bore with a
right-handed threaded portion and a left-handed threaded portion
having a smaller diameter than the right-handed threaded portion.
An insertion device with a right-handed threaded portion can be
engaged with the right-handed threaded portion of the screw bore to
screw the screw into a prepared screw socket. A left-handed
threaded extraction device can be engaged with the left-handed
portion of the internal bore to extract the screw. The screw can be
fixed by inserting a wire in a radial bore disposed in a rearward
portion of the screw for removal of the insertion or extraction
devices without disturbing the placement of the screw.
In the method for fixation of the tendon/bone graft, a
bone-tendon-bone graft is harvested from the patellar tendon. Each
bone plug of the bone-tendon-bone graft is harvested in a
semicircular cross-section with a semicircular gouge and is
conventionally sized. A graft socket is then drilled into the bone
with an anti-cavitational drill. The bone surrounding the drilled
socket is compacted by sizing the socket with a series of
increasingly larger tubular sizing instruments until the compacted
socket is sized to accomodate the bone plug.
The bone plug is then inserted into the compacted socket and
positioned as desired. The bone plug may be held in place by a
conventional K-wire or with sutures, if necessary. The bone plug is
compacted into the compacted socket by inserting a series of
increasingly larger tubular dilating instruments between the
compacted socket and the bone plug, thereby forming a screw socket.
After the largest dilating instrument has been used, the compacting
of the socket and bone plug can be continued with the larger sizing
instruments as discussed above. When the next larger size sizing
instrument cannot be manually inserted into the screw socket, the
screw size is chosen to be the same as the size of the compacted
screw socket, i.e., the same size as the last dilating or sizing
instrument that could be inserted into the screw socket.
The sized screw is then screwed onto the insertion tool, whereupon
the screw is threaded into the screw socket, thereby securing the
bone plug to the bone. If necessary, an extraction tool can be
screwed into the left-handed threaded portion of the internal bore
to extract the screw, either slightly or entirely. The same method
is also carried out with the other bone plug of the
bone-tendon-bone graft, with the method steps for fixing the two
bone plugs overlapping. The remainder of the surgical operation
proceeds conventionally.
Thus, the screw of the present invention enters a precreated
unthreaded, smooth wall screw socket of compressed bone, thereby
creating a maximum tight fit for the screw threads and a
side-to-side compression fit between the bone plug and bone. The
precreated screw socket prevents divergence of the screw and
migration of the graft. Only the initial socket is drilled and
threads are not cut into the bone or bone plug, thereby preventing
cutting and fragmentation of the bone plug. Rather, the screw fixes
the bone plug through the use of displacement and compression. The
screw need not be made of expensive alloys but can be constructed
of surgical stainless steel.
With the foregoing in mind, other objects, features and advantages
of the present invention will become more apparent upon
consideration of the following description and the appended claims
with reference to the accompanying drawings, all of which form part
of this specification, wherein like reference numerals designate
corresponding parts in the various figures.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevational view of the fixation screw of the
present invention;
FIG. 2 is a rear elevational of the fixation screw;
FIG. 3 is a sectional view taken along section line 3--3 of FIG.
2;
FIG. 4 is a side elevational view of a patient's knee showing the
fixation screws of the present invention fixing a bone-tendon-bone
graft;
FIG. 5 is an end elevational view of the semicircular harvested
bone plug;
FIG. 6 is a side elevational view of a sizing instrument;
FIG. 7 is a side elevational view of a dilating instrument; and
FIG. 8 is a schematic diagram illustrating the steps for preparing
bone for receiving a medical device or biological material by
sizing a bore in bone and compacting the internal wall of the bore
in accordance with the present invention; and
FIG. 9 schematically illustrates the results of preparing bone for
receiving a medical device or biological material in accordance
with prior art methods and in accordance with the present
invention.
DESCRIPTION OF THE PREFERRED EXEMPLARY EMBODIMENT
FIGS. 1-3 show a preferred embodiment of a fixation screw 10
according to the present invention. The screw has a smooth conical
forward end 12 with a rounded tip 14 and is of a headless design. A
right-handed spiral thread 16 runs from a position behind the
smooth conical forward end 14 to a rearward end 18 of the screw 10.
The depth of the thread 16 is shallower than conventional
interference screws and the thread 16 has a rounded exterior edge
20 and root to decrease cutting and fragmentation of the bone.
The screw includes an internal longitudinal bore 22 with a
right-handed threaded portion 24 and a smaller diameter left-handed
threaded portion 26 nearer the forward end 12. A right-handed
threaded insertion device (not shown) can be engaged with the
right-handed threaded portion 24 for screwing the fixation screw 10
into a prepared screw socket. A left-handed threaded insertion
device (not shown) can be engaged with the left-handed threaded
portion 26 for extraction of the screw 10. Of course, in an
alternative embodiment, spiral thread 16 and threaded portion 24
can be left-handed while threaded portion 26 is right-handed.
The screw 10 further includes a radial bore 28 located near the
rearward end 18. A wire (not shown) can be placed in the bore 28 to
prevent rotation of the screw 10 while the insertion or extraction
device is being removed from the screw 10. In the preferred
embodiment, the screw 10 is made from surgical stainless steel and
need not be made from an expensive alloy. Of course, other
appropriate materials can also be used as well known in the art,
including biodegradable material.
In the preferred embodiment, the screw 10 is 25 to 40 mm long and
has 5 threads/inch, regardless of the outer diameter of the screw
10, which can be 5, 7, 9, 11 or 13 mm. The exterior edge 20 and
root 21 are rounded to a 0.02 inch radius and the height of the
thread 16 from root 21 to exterior edge 20 is 0.065 inch. The
thread 16 does not extend diametrically beyond the largest outer
diameter of the conical forward end 12. The forward end 12 has an
angle of 28 degrees from a longitudinal axis of the screw to the
exterior conical surface of the forward end 12. Threaded portion 24
has an 8-32 right-handed thread and threaded portion 26 has a 6-32
left-handed thread.
In the method for fixation of the tendon/bone graft, for instance,
in arthroscopic reconstruction of the anterior cruciate ligament, a
bone-tendon-bone graft is harvested from the patellar tendon, as
conventionally known. Each bone plug 30 of the bone-tendon-bone
graft is harvested in a semicircular cross-section, as shown in
FIG. 5, with a semicircular gouge. Reference can also be made to
FIG. 4 which shows the bone-tendon-bone graft 40 secured in a
patient's knee 42 with the fixation screws 10. The size of the
bone-tendon-bone graft is predetermined for each individual patient
and in the preferred embodiments, a 9, 10 or 11 mm (and 12 & 13
mm) diameter semicircular bone plug 30 is harvested on each end of
the bone-tendon-bone graft. Each bone plug is then conventionally
shaped and sized to the desired dimensions.
Next, a blind graft socket 44 is drilled in the femur 46 with an
anti-cavitational drill, which is provided in 8, 9, 10 and 11 mm
diameters. The anti-cavitational drill does not have an acorn-type
head that can drill out-of-round holes or cavitate the graft
socket, thereby deteriorating the bone plug to graft socket fit.
Rather, the drill has straight sides with a rounded tip. A through
socket can also be drilled if desired or for a different
application. The size of the drill is chosen to be smaller than the
size of the bone plug 30. For instance, if the bone plug 30 is 11
mm, an 8 mm graft socket is initially drilled.
The bone surrounding the graft socket 44 is then compacted and the
graft socket 44 enlarged and sized by manually inserting a sizing
instrument 32 having a larger diameter than the selected drill into
the graft socket 44. The sizing instrument 32 is shown in FIG. 6
and is tubular with a blunt forward end 34 having rounded edges.
The sizing instrument 32 can also have a conical or other shape
forward end in an alternative embodiment.
The sizing of the graft socket 44 is preferably done serially with
increasingly larger sizing instruments 32 until the graft socket 44
has been sized to the size of the bone plug 30 and the surrounding
bone has been firmly compacted. During the sizing of the socket 44,
no bone is intended to be removed, but instead the bone is
outwardly displaced within the cavity, thereby compacting the bone
surrounding the socket 44. This provides denser and stronger bone
surrounding the socket which is able to withstand higher stress
than the uncompacted bone. If the graft socket 44 cannot be sized
large enough for the harvested bone plug 30, preferably the graft
socket 44 would be redrilled with a larger drill and then resized,
if necessary, as discussed above. This will depend on the hardness
of the bone and the degree of compaction of the bone that can
achieved. Alternatively, the bone plug 30 can be resized to be
smaller to fit the sized graft socket 44.
The sized bone plug 30 of the bone-tendon-bone graft is then
inserted into the sized graft socket 44 to the bottom of the graft
socket 44 and positioned as desired. The placement of the
bone-tendon-bone graft 40 can be eased with the use of a standard
guide wire inserted into the graft. If necessary, the bone plug can
be held in place by a conventional K-wire or with sutures. The bone
plug 30 is compacted into the graft socket 44 with a smooth tubular
dilating instrument 36 having a conical forward end 38, as shown in
FIG. 7. In an alternative embodiment, the forward end 38 can be
more blunt or more rounded or have another shape.
The dilating instrument is provided in 4, 5, 6, 7 and 8 mm sizes
and is inserted into the cavity between the semicircular bone plug
30 and the graft socket 44 to compact the bone plug 30, further
compact the graft socket 44 and to size a screw socket for
receiving the fixation screw 10. As with the sizing of the graft
socket 44, the compacting of the bone plug is done serially with
increasingly larger diameter dilating instruments 36 and sizing
instruments 32 until the desired diameter screw socket is achieved
or until the next larger dilating instrument 36 or sizing
instrument 34 cannot be manually inserted into the screw socket.
Preferably, the screw socket is sized to be smaller in diameter
than the sized bone plug 30. For instance, if a 10 mm bone plug is
used, the screw socket would only be sized to 8 mm, for use with an
8 mm diameter screw 10. A screw having a larger diameter than the
screw socket can also be used, if even further compaction of the
graft socket and bone plug is desired.
The screw 10 is then screwed onto the insertion device for
insertion into the screw socket. The screw 10 is screwed into the
screw socket until it bottoms, then is turned an additional small
amount to make certain that everything is secure. If a blind graft
socket was not used, then the screw 10 is screwed in until it
reaches a desired position. The insertion device can then be
removed from the screw 10. If necessary, a wire can be temporarily
inserted into the radial bore 28 to secure the screw 10 while the
insertion device is being removed. If extraction of the screw 10 is
necessary, the extraction device can now be used.
The same method is used for the second bone plug 30 of the
bone-tendon-bone graft 40, with the method steps for fixing the two
bone plugs 30 overlapping. Any undiscussed portions of the surgical
operation proceed conventionally. After 4 to 6 weeks there will be
a bony union between the bone plugs and the femur and tibia,
respectively, and the fixation screws will no longer have any
function. The screws will not generally be removed at this time,
although they can be.
The method for preparing bone which has been described above is
schematically illustrated in FIG. 8, and a comparison of the
results of such preparation and those obtained by known methods is
shown in FIG. 9. More particularly, FIG. 8 illustrates a
cylindrical bore having a diameter d.sub.0 into which dilating and
compacting instruments having increasing larger diameters, d.sub.1
-d.sub.3, are successively inserted to increase the diameter of the
bore and compact the bone surrounding the wall of the bore. The
results of such compaction are indicated in FIG. 9 wherein the bone
density of the bore's wall is shown to be significantly greater
than that obtainable by merely forming the bore to the correct size
in accordance with known techniques.
Although the procedure discussed above is in reference to
reconstruction of the anterior cruciate ligament, it should be
realized that the screw and method of the present invention can be
used in other ligament/tendon reconstructive applications,
arthroscopic or otherwise. Further, the sizes and shapes of the
drills, screws, sizing instruments and dilating instruments can
also be altered as necessary. The screws 10 and drills can be
cannulated for use with a guide wire, as conventionally known.
The method of preparing the bone for receiving the screw can also
be used in many other surgical operations.
While the invention has been described in accordance with what is
presently conceived to be the most practical and preferred
embodiment, it is to be understood that the invention is not to be
limited to the disclosed embodiment but on the contrary, is
intended to cover various modifications and equivalent arrangements
included within the spirit and the scope of the appended claims,
which scope is to be accorded the broadest interpretation of such
claims so as to encompass all such equivalent structures.
* * * * *